[Hot Reload with dotnet watch] Create a Blazor Web App project, update the .css file, the browser updates the display colors, then refresh the browser, and the project will revert to its previous state

[EmilyFeng97]

REGRESSION INFO Works well on 10.0/9.0/8.0 and previous build 11.0.100-alpha.1.26060.102

INSTALL STEPS

1. Clean Win11 x64 23h2 ENU
2. Install the .NET 11.0 preview 1 SDK: https://aka.ms/dotnet/11.0.1xx/daily/dotnet-sdk-win-x64.exe
3. Add feed: https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet11/nuget/v3/index.json

Platform

• Windows
• macOS
• Linux

Repro Steps

1. Open a normal Command Prompt
2. Create a Blazor Web App for Server project, and run it using dotnet watch

   dotnet new blazor -int Server -o MyBlazorServerApp
   cd MyBlazorServerApp
   dotnet watch
   

3. Open Components/Layout/MainLayout.razor.css in Notepad, update the .page selector:

   .page {
       position: relative;
       display: flex;
       flex-direction: column;
   +   background-color: orange;
   

4. Save the change, the browser update to display the color
5. Refresh the browser, view the browser

Actual Result
The page will return to the previous state after refresh the browser.

Note:

1. This issue does not repro on 10.0/9.0/8.0 project.
2. This issue does not repro Blazor WebAssembly Standalone project.
3. This issue also repro on Blazor web app for Wasm project.
4. The issue does not repro when hot reload in vs 18.4I1.
5. This issue also repro on wwwroot/app.css file, does not repro on .razor file.

Error Log

[ilonatommy]

@EmilyFeng97, thank you for your report.

Could you please collect the detailed logs for hot reload, after passing --verbose option?

[EmilyFeng97]

@EmilyFeng97, thank you for your report.

Could you please collect the detailed logs for hot reload, after passing --verbose option?

The following is a detailed log of hot reload when reproducing this bug:

detailed log

C:\Users\v-xinyfe\MyBlazorServerApp>dotnet watch --verbose dotnet watch ⌚ Working directory: 'C:\Users\v-xinyfe\MyBlazorServerApp' dotnet watch ⌚ Watching with Hot Reload. dotnet watch 🔥 Hot reload enabled. For a list of supported edits, see https://aka.ms/dotnet/hot-reload. dotnet watch 💡 Press Ctrl+R to restart. dotnet watch 🔨 Building C:\Users\v-xinyfe\MyBlazorServerApp\MyBlazorServerApp.csproj ... dotnet watch 🚀 Launched 'C:\Program Files\dotnet\dotnet.exe' with arguments 'build C:\Users\v-xinyfe\MyBlazorServerApp\MyBlazorServerApp.csproj -consoleLoggerParameters:NoSummary;Verbosity=minimal --property:NuGetInteractive=true': process id 14644 Restore complete (0.4s) info NETSDK1057: You are using a preview version of .NET. See: https://aka.ms/dotnet-support-policy MyBlazorServerApp net11.0 succeeded (6.5s) → bin\Debug\net11.0\MyBlazorServerApp.dll

Build succeeded in 7.7s
dotnet watch ⌚ Process id 14644 ran for 9298ms and exited with exit code 0.
dotnet watch ⌚ Evaluating projects ...
dotnet watch ⌚ Watching 66 file(s) for changes
dotnet watch ⌚ Evaluation completed in 1.3s.
dotnet watch ⌚ Exclusion glob: '\node_modules*;node_modules*;\jspm_packages*;jspm_packages*;\bower_components*;bower_components*;\packages.lock.json;bin\Debug/;obj\Debug/;bin/;obj/;bin\Debug\net11.0\publish/;/.user;**/.proj;**/.sln;/*.slnx;/*.vssscc;/.DS_Store' under project 'C:\Users\v-xinyfe\MyBlazorServerApp'
dotnet watch ⌚ Application kind: WebApplication.
dotnet watch 🔃 [MyBlazorServerApp (net11.0)] Using browser-refresh middleware
dotnet watch 🔃 [MyBlazorServerApp (net11.0)] Refresh server running at wss://localhost:53047,ws://localhost:53048.
dotnet watch ⌚ dotnet-watch is configured to launch a browser on ASP.NET Core application startup.
dotnet watch 🔥 [MyBlazorServerApp (net11.0)] Waiting for application to connect to pipe 959772fe37e94b86b4c221490969f4ac.
dotnet watch 🚀 [MyBlazorServerApp (net11.0)] Launched 'C:\Program Files\dotnet\dotnet.exe' with arguments 'run --no-build -e DOTNET_WATCH=1 -e DOTNET_WATCH_ITERATION=1 -e "HOTRELOAD_DELTA_CLIENT_LOG_MESSAGES=dotnet watch 🕵️ [MyBlazorServerApp (net11.0)]" -e DOTNET_MODIFIABLE_ASSEMBLIES=debug -e "DOTNET_STARTUP_HOOKS=C:\Program Files\dotnet\sdk\11.0.100-preview.1.26071.101\DotnetTools\dotnet-watch\11.0.100-preview.1.26071.101\tools\net11.0\any\hotreload\net6.0\Microsoft.AspNetCore.Watch.BrowserRefresh.dll;C:\Program Files\dotnet\sdk\11.0.100-preview.1.26071.101\DotnetTools\dotnet-watch\11.0.100-preview.1.26071.101\tools\net11.0\any\hotreload\net11.0\Microsoft.Extensions.DotNetDeltaApplier.dll" -e DOTNET_WATCH_HOTRELOAD_NAMEDPIPE_NAME=959772fe37e94b86b4c221490969f4ac -e ASPNETCORE_AUTO_RELOAD_WS_ENDPOINT=wss://localhost:53047,ws://localhost:53048 -e ASPNETCORE_AUTO_RELOAD_WS_KEY=MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAtctetuD/jrheShuiiYsF2zlnbzmx5mBYf1omt+z8lkqBjvKh6jxddIgPrqA6bEt+etD+kcDc8m4ie/+B/HIWbUY61cvc2L4evJqdomoPl9quFrlvm6A8rFeW4H/WgO7h5qdTo4dt5glQHKyjMxEuvEbUaH4xeuQzqZGYn2BoWZiN8uXsRIgkR31+AXMpA3iYJBHGGcmal3rxzL4CZkTAZmMtwpJ5GxkG88uhpkhyKWab9brlkjMLUGY3cfNOz7UHvBTkO+4rdEzURU1U8UE4ifEZIwO7uYPpLq4luxeSp69RgZ9E2R6797kKzAgZ3xYqUkNO5Nyh8ZaJ2kuq8+7VmQIDAQAB -e ASPNETCORE_AUTO_RELOAD_VDIR=/ -e ASPNETCORE_HOSTINGSTARTUPASSEMBLIES=Microsoft.AspNetCore.Watch.BrowserRefresh -e Logging__LogLevel__Microsoft.AspNetCore.Watch=Debug': process id 2908
Using launch settings from C:\Users\v-xinyfe\MyBlazorServerApp\Properties\launchSettings.json...
dotnet watch 🕵️ [MyBlazorServerApp (net11.0)] Loaded into process: C:\Users\v-xinyfe\MyBlazorServerApp\bin\Debug\net11.0\MyBlazorServerApp.dll (C:\Program Files\dotnet\sdk\11.0.100-preview.1.26071.101\DotnetTools\dotnet-watch\11.0.100-preview.1.26071.101\tools\net11.0\any\hotreload\net11.0\Microsoft.Extensions.DotNetDeltaApplier.dll)
dotnet watch 🕵️ [MyBlazorServerApp (net11.0)] Windows Ctrl+C handling enabled.
dotnet watch 🕵️ [MyBlazorServerApp (net11.0)] Connecting to hot-reload server via pipe 959772fe37e94b86b4c221490969f4ac
dotnet watch 🕵️ [MyBlazorServerApp (net11.0)] Connected.
dotnet watch 🔥 [MyBlazorServerApp (net11.0)] Capabilities: 'Baseline AddMethodToExistingType AddStaticFieldToExistingType AddInstanceFieldToExistingType NewTypeDefinition ChangeCustomAttributes UpdateParameters GenericUpdateMethod GenericAddMethodToExistingType GenericAddFieldToExistingType AddFieldRva AddExplicitInterfaceImplementation'.
dotnet watch ⌚ Loading projects ...
dbug: Microsoft.AspNetCore.Watch.BrowserRefresh.BlazorWasmHotReloadMiddleware[0]
Middleware loaded
dbug: Microsoft.AspNetCore.Watch.BrowserRefresh.BrowserScriptMiddleware[0]
Middleware loaded. Script /_framework/aspnetcore-browser-refresh.js (14901 B).
dbug: Microsoft.AspNetCore.Watch.BrowserRefresh.BrowserScriptMiddleware[0]
Middleware loaded. Script /_framework/blazor-hotreload.js (799 B).
dbug: Microsoft.AspNetCore.Watch.BrowserRefresh.BrowserRefreshMiddleware[0]
Middleware loaded: DOTNET_MODIFIABLE_ASSEMBLIES=debug, __ASPNETCORE_BROWSER_TOOLS=true
info: Microsoft.Hosting.Lifetime[14]
Now listening on: http://localhost:5202
dotnet watch ⌚ Launching browser: http://localhost:5202
dotnet watch 🚀 Launched 'http://localhost:5202' with arguments '': process id 12888
info: Microsoft.Hosting.Lifetime[0]
Application started. Press Ctrl+C to shut down.
info: Microsoft.Hosting.Lifetime[0]
Hosting environment: Development
info: Microsoft.Hosting.Lifetime[0]
Content root path: C:\Users\v-xinyfe\MyBlazorServerApp
warn: Microsoft.AspNetCore.HttpsPolicy.HttpsRedirectionMiddleware[3]
Failed to determine the https port for redirect.
dbug: Microsoft.AspNetCore.Watch.BrowserRefresh.BrowserRefreshMiddleware[1]
Response markup is scheduled to include browser refresh script injection.
dbug: Microsoft.AspNetCore.Watch.BrowserRefresh.BrowserRefreshMiddleware[2]
Response markup was updated to include browser refresh script injection.
dbug: Microsoft.AspNetCore.Watch.BrowserRefresh.BrowserScriptMiddleware[0]
Script injected: /_framework/aspnetcore-browser-refresh.js
dotnet watch ⌚ Projects loaded in 1.7s.
dotnet watch 🔥 Hot reload session started.
dotnet watch ⌚ Waiting for changes
dotnet watch 🌐 [Browser #1] Connected to refresh server.
dotnet watch ⌚ [FW] Updated 'C:\Users\v-xinyfe\MyBlazorServerApp\Components\Layout\MainLayout.razor.css'.
dotnet watch ⌚ File change: Update 'C:\Users\v-xinyfe\MyBlazorServerApp\Components\Layout\MainLayout.razor.css'.
dotnet watch ⌚ File updated: .\Components\Layout\MainLayout.razor.css
dotnet watch ⌚ Handling file change event for scoped css file C:\Users\v-xinyfe\MyBlazorServerApp\Components\Layout\MainLayout.razor.css.
dotnet watch ⌚ [FW] Updated 'C:\Users\v-xinyfe\MyBlazorServerApp\obj\Debug\net11.0\rpswa.dswa.cache.json'.
dotnet watch ⌚ Ignoring change in excluded file 'C:\Users\v-xinyfe\MyBlazorServerApp\obj\Debug\net11.0\rpswa.dswa.cache.json': Update. Path matches DefaultItemExcludes glob 'obj\Debug/' set in 'C:\Users\v-xinyfe\MyBlazorServerApp'.
dotnet watch ⌚ [FW] Updated 'C:\Users\v-xinyfe\MyBlazorServerApp\obj\Debug\net11.0\rpswa.dswa.cache.json'.
dotnet watch ⌚ Ignoring change in excluded file 'C:\Users\v-xinyfe\MyBlazorServerApp\obj\Debug\net11.0\rpswa.dswa.cache.json': Update. Path matches DefaultItemExcludes glob 'obj\Debug/' set in 'C:\Users\v-xinyfe\MyBlazorServerApp'.
dotnet watch ⌚ [FW] Updated 'C:\Users\v-xinyfe\MyBlazorServerApp\obj\Debug\net11.0\rjsmrazor.dswa.cache.json'.
dotnet watch ⌚ Ignoring change in excluded file 'C:\Users\v-xinyfe\MyBlazorServerApp\obj\Debug\net11.0\rjsmrazor.dswa.cache.json': Update. Path matches DefaultItemExcludes glob 'obj\Debug/' set in 'C:\Users\v-xinyfe\MyBlazorServerApp'.
dotnet watch ⌚ [FW] Updated 'C:\Users\v-xinyfe\MyBlazorServerApp\obj\Debug\net11.0\rjsmrazor.dswa.cache.json'.
dotnet watch ⌚ Ignoring change in excluded file 'C:\Users\v-xinyfe\MyBlazorServerApp\obj\Debug\net11.0\rjsmrazor.dswa.cache.json': Update. Path matches DefaultItemExcludes glob 'obj\Debug/' set in 'C:\Users\v-xinyfe\MyBlazorServerApp'.
dotnet watch ⌚ [FW] Updated 'C:\Users\v-xinyfe\MyBlazorServerApp\obj\Debug\net11.0\rjsmcshtml.dswa.cache.json'.
dotnet watch ⌚ Ignoring change in excluded file 'C:\Users\v-xinyfe\MyBlazorServerApp\obj\Debug\net11.0\rjsmcshtml.dswa.cache.json': Update. Path matches DefaultItemExcludes glob 'obj\Debug/' set in 'C:\Users\v-xinyfe\MyBlazorServerApp'.
dotnet watch ⌚ [FW] Updated 'C:\Users\v-xinyfe\MyBlazorServerApp\obj\Debug\net11.0\rjsmcshtml.dswa.cache.json'.
dotnet watch ⌚ Ignoring change in excluded file 'C:\Users\v-xinyfe\MyBlazorServerApp\obj\Debug\net11.0\rjsmcshtml.dswa.cache.json': Update. Path matches DefaultItemExcludes glob 'obj\Debug/' set in 'C:\Users\v-xinyfe\MyBlazorServerApp'.
dotnet watch ⌚ [FW] Updated 'C:\Users\v-xinyfe\MyBlazorServerApp\obj\Debug\net11.0\scopedcss\Components\Layout\ReconnectModal.razor.rz.scp.css'.
dotnet watch ⌚ Ignoring change in excluded file 'C:\Users\v-xinyfe\MyBlazorServerApp\obj\Debug\net11.0\scopedcss\Components\Layout\ReconnectModal.razor.rz.scp.css': Update. Path matches DefaultItemExcludes glob 'obj\Debug/' set in 'C:\Users\v-xinyfe\MyBlazorServerApp'.
dotnet watch ⌚ [FW] Updated 'C:\Users\v-xinyfe\MyBlazorServerApp\obj\Debug\net11.0\scopedcss\Components\Layout\MainLayout.razor.rz.scp.css'.
dotnet watch ⌚ Ignoring change in excluded file 'C:\Users\v-xinyfe\MyBlazorServerApp\obj\Debug\net11.0\scopedcss\Components\Layout\MainLayout.razor.rz.scp.css': Update. Path matches DefaultItemExcludes glob 'obj\Debug/' set in 'C:\Users\v-xinyfe\MyBlazorServerApp'.
dotnet watch ⌚ [FW] Updated 'C:\Users\v-xinyfe\MyBlazorServerApp\obj\Debug\net11.0\scopedcss\Components\Layout\NavMenu.razor.rz.scp.css'.
dotnet watch ⌚ Ignoring change in excluded file 'C:\Users\v-xinyfe\MyBlazorServerApp\obj\Debug\net11.0\scopedcss\Components\Layout\NavMenu.razor.rz.scp.css': Update. Path matches DefaultItemExcludes glob 'obj\Debug/' set in 'C:\Users\v-xinyfe\MyBlazorServerApp'.
dotnet watch ⌚ [FW] Updated 'C:\Users\v-xinyfe\MyBlazorServerApp\obj\Debug\net11.0\scopedcss\Components\Layout\MainLayout.razor.rz.scp.css'.
dotnet watch ⌚ Ignoring change in excluded file 'C:\Users\v-xinyfe\MyBlazorServerApp\obj\Debug\net11.0\scopedcss\Components\Layout\MainLayout.razor.rz.scp.css': Update. Path matches DefaultItemExcludes glob 'obj\Debug/' set in 'C:\Users\v-xinyfe\MyBlazorServerApp'.
dotnet watch ⌚ [FW] Updated 'C:\Users\v-xinyfe\MyBlazorServerApp\obj\Debug\net11.0\scopedcss\Components\Layout\ReconnectModal.razor.rz.scp.css'.
dotnet watch ⌚ Ignoring change in excluded file 'C:\Users\v-xinyfe\MyBlazorServerApp\obj\Debug\net11.0\scopedcss\Components\Layout\ReconnectModal.razor.rz.scp.css': Update. Path matches DefaultItemExcludes glob 'obj\Debug/' set in 'C:\Users\v-xinyfe\MyBlazorServerApp'.
dotnet watch ⌚ [FW] Updated 'C:\Users\v-xinyfe\MyBlazorServerApp\obj\Debug\net11.0\scopedcss\Components\Layout\NavMenu.razor.rz.scp.css'.
dotnet watch ⌚ Ignoring change in excluded file 'C:\Users\v-xinyfe\MyBlazorServerApp\obj\Debug\net11.0\scopedcss\Components\Layout\NavMenu.razor.rz.scp.css': Update. Path matches DefaultItemExcludes glob 'obj\Debug/' set in 'C:\Users\v-xinyfe\MyBlazorServerApp'.
dotnet watch ⌚ [FW] Updated 'C:\Users\v-xinyfe\MyBlazorServerApp\obj\Debug\net11.0\scopedcss\bundle\MyBlazorServerApp.styles.css'.
dotnet watch ⌚ Ignoring change in excluded file 'C:\Users\v-xinyfe\MyBlazorServerApp\obj\Debug\net11.0\scopedcss\bundle\MyBlazorServerApp.styles.css': Update. Path matches DefaultItemExcludes glob 'obj\Debug/' set in 'C:\Users\v-xinyfe\MyBlazorServerApp'.
dotnet watch ⌚ [FW] Updated 'C:\Users\v-xinyfe\MyBlazorServerApp\obj\Debug\net11.0\scopedcss\bundle\MyBlazorServerApp.styles.css'.
dotnet watch ⌚ Ignoring change in excluded file 'C:\Users\v-xinyfe\MyBlazorServerApp\obj\Debug\net11.0\scopedcss\bundle\MyBlazorServerApp.styles.css': Update. Path matches DefaultItemExcludes glob 'obj\Debug/' set in 'C:\Users\v-xinyfe\MyBlazorServerApp'.
dotnet watch ⌚ [FW] Updated 'C:\Users\v-xinyfe\MyBlazorServerApp\obj\Debug\net11.0\scopedcss\projectbundle\MyBlazorServerApp.bundle.scp.css'.
dotnet watch ⌚ Ignoring change in excluded file 'C:\Users\v-xinyfe\MyBlazorServerApp\obj\Debug\net11.0\scopedcss\projectbundle\MyBlazorServerApp.bundle.scp.css': Update. Path matches DefaultItemExcludes glob 'obj\Debug/' set in 'C:\Users\v-xinyfe\MyBlazorServerApp'.
dotnet watch ⌚ [FW] Updated 'C:\Users\v-xinyfe\MyBlazorServerApp\obj\Debug\net11.0\scopedcss\projectbundle\MyBlazorServerApp.bundle.scp.css'.
dotnet watch ⌚ Ignoring change in excluded file 'C:\Users\v-xinyfe\MyBlazorServerApp\obj\Debug\net11.0\scopedcss\projectbundle\MyBlazorServerApp.bundle.scp.css': Update. Path matches DefaultItemExcludes glob 'obj\Debug/' set in 'C:\Users\v-xinyfe\MyBlazorServerApp'.
dotnet watch 🔃 [MyBlazorServerApp (net11.0)] Sending static asset update request to connected browsers: 'MyBlazorServerApp.css'.
dotnet watch 🔥 Hot reload of scoped css succeeded.
dotnet watch 🔥 Hot reload capabilities: AddExplicitInterfaceImplementation AddFieldRva AddInstanceFieldToExistingType AddMethodToExistingType AddStaticFieldToExistingType Baseline ChangeCustomAttributes GenericAddFieldToExistingType GenericAddMethodToExistingType GenericUpdateMethod NewTypeDefinition UpdateParameters.
dotnet watch ⌚ No C# changes to apply.
dotnet watch 🔃 [MyBlazorServerApp (net11.0)] Updating diagnostics.
dotnet watch 🔥 Hot reload change handled in 386ms.
dotnet watch ⌚ [FW] Updated 'C:\Users\v-xinyfe\MyBlazorServerApp\obj\Debug\net11.0\rjsmrazor.dswa.cache.json'.
dotnet watch ⌚ Ignoring change in excluded file 'C:\Users\v-xinyfe\MyBlazorServerApp\obj\Debug\net11.0\rjsmrazor.dswa.cache.json': Update. Path matches DefaultItemExcludes glob 'obj\Debug/' set in 'C:\Users\v-xinyfe\MyBlazorServerApp'.
dotnet watch ⌚ [FW] Updated 'C:\Users\v-xinyfe\MyBlazorServerApp\obj\Debug\net11.0\rpswa.dswa.cache.json'.
dotnet watch ⌚ Ignoring change in excluded file 'C:\Users\v-xinyfe\MyBlazorServerApp\obj\Debug\net11.0\rpswa.dswa.cache.json': Update. Path matches DefaultItemExcludes glob 'obj\Debug/' set in 'C:\Users\v-xinyfe\MyBlazorServerApp'.
dotnet watch ⌚ [FW] Updated 'C:\Users\v-xinyfe\MyBlazorServerApp\obj\Debug\net11.0\rjsmcshtml.dswa.cache.json'.
dotnet watch ⌚ Ignoring change in excluded file 'C:\Users\v-xinyfe\MyBlazorServerApp\obj\Debug\net11.0\rjsmcshtml.dswa.cache.json': Update. Path matches DefaultItemExcludes glob 'obj\Debug/' set in 'C:\Users\v-xinyfe\MyBlazorServerApp'.
dotnet watch ⌚ [FW] Updated 'C:\Users\v-xinyfe\MyBlazorServerApp\obj\Debug\net11.0\rjimswa.dswa.cache.json'.
dotnet watch ⌚ Ignoring change in excluded file 'C:\Users\v-xinyfe\MyBlazorServerApp\obj\Debug\net11.0\rjimswa.dswa.cache.json': Update. Path matches DefaultItemExcludes glob 'obj\Debug/**' set in 'C:\Users\v-xinyfe\MyBlazorServerApp'.
dbug: Microsoft.AspNetCore.Watch.BrowserRefresh.BrowserRefreshMiddleware[1]
Response markup is scheduled to include browser refresh script injection.
dbug: Microsoft.AspNetCore.Watch.BrowserRefresh.BrowserRefreshMiddleware[2]
Response markup was updated to include browser refresh script injection.
dbug: Microsoft.AspNetCore.Watch.BrowserRefresh.BrowserScriptMiddleware[0]
Script injected: /_framework/aspnetcore-browser-refresh.js
dotnet watch 🌐 [Browser #2] Connected to refresh server.
info: Microsoft.Hosting.Lifetime[0]
Application is shutting down...
dotnet watch 🛑 Shutdown requested. Press Ctrl+C again to force exit.
dotnet watch ⌚ Terminating remaining child processes.
dotnet watch ⌚ [MyBlazorServerApp (net11.0)] Terminating process 2908 (Ctrl+C).
dotnet watch ⌚ [MyBlazorServerApp (net11.0)] Waiting for process 2908 to exit within 5s.
dotnet watch ⌚ [MyBlazorServerApp (net11.0)] Process id 2908 ran for 37594ms and exited with exit code 0.
dotnet watch ⌚ [MyBlazorServerApp (net11.0)] Exited
dotnet watch 🔥 [MyBlazorServerApp (net11.0)] Disposing agent communication pipe
dotnet watch 🌐 [Browser #1] Disconnected.
dotnet watch 🌐 [Browser #2] Disconnected.

[ilonatommy]

@EmilyFeng97, I tried with 11.0.100-preview.1.26067.103 and I cannot reproduce.

[EmilyFeng97]

@EmilyFeng97, I tried with 11.0.100-preview.1.26067.103 and I cannot reproduce.

I verify this on "11.0.100-preview.1.26073.123" SDK, I can still reproduce it.
This is a virtual machine (IP address: 10.170.194.120) with 11.0 SDK installed. You can connect using your Microsoft account at any time . Please contact me if you have any questions.

[ilonatommy]

Got it. I was checking on chrome that works fine, the bug manifests on edge.
Checking networking tab, it's a cache problem. All requests are sent with no-cache.

#	Step	Code	Behavior	Etag
1	Initial load	304	Uses cache (white)	X
2	Hot reload with ?nonce (different request than in step 1)	200	Fresh fetch (orange)	Y
3	F5 refresh	304	Uses cache (white)	X
4	Ctrl+Shift+R refresh	200	Bypasses cache (orange)	Y

#64611 might have exposed this bug. Before, most of the requests were returning 200 due to incorrect timestamp comparison.

Edit:
It's most probably caused by the server comparing the changes against the manifest file (staticwebassets.build.endpoints.json) with etag from step 1 when the request for step 3 comes. The manifest is created in build time, it keeps the etag of step 1. Hot reload used a different url, its updates are not bound to the 1st or 3rd request. Because of that, when request 3 comes, browser treats step 1 as "the latest" version of file and sends it to the server for comparison. Server takes it and compares with the manifest -> their etags are same -> responds with 304 -> browser gets a confirmation to use the version from step 1.

Theoretically we could either update manifest on each hot reload change or not append the query to hot reload requests so that the latest file comes from step 2. I don't believe it's this simple, though.

[ilonatommy]

@tmat, this looks like a blocker for p1, any thought if any of the proposed solutions make sense?

[tmat]

@ilonatommy Does it repro with a combination of the latest SDK from release/10.0.3xx branch and ASP.NET bits that have #64611?

[ilonatommy]

Does it repro with a combination of the latest SDK from release/10.0.3xx branch and ASP.NET bits that have #64611

That would be net11 app with net10 sdk - not supported combination. I cherry-picked that change and ported it to asp.net 10.
I cannot reproduce the problem, all the responses are 200, css persists, requests table:

Step	Action	Status	Behavior	ETag
1	Initial load	200	Fresh (white)	X
2	Hot reload with ?nonce	200	Fresh fetch (orange)	Y
3	F5 refresh (no nonce)	200	Fresh (orange)	Y
4	Hard refresh	200	Fresh (orange)	Y

The manifest modification timestamp is in line with build timestamp.

[tmat]

Cool. It might have been fixed by dotnet/sdk#52225.